Orodispersible Tablets: A Comprehensive Review

 

Jaybhaye Aarti*, Joshi Sonali, Deshmukh Ganesh

Oriental College of Pharmacy, Plot No. 3, 4,5, Sector-2, Sanpada, Navi Mumbai-400705

*Corresponding Author E-mail: 2008aartij@gmail.com

 

 

ABSTRACT:

Oral drug delivery remains the most preferred route for administration of various therapeutic agents. Recent advances in technology prompted researchers and scientists to develop orodispersible tablets (ODTs) with improved patient convenience and compliance. ODTs are solid unit dosage form which dissolve or disintegrate rapidly in the mouth without water or chewing. Over the past three decades, orodispersible tablets (ODTs) have gained considerable attention as a preferred alternative to conventional tablets and capsules due to better patient compliance, improved solubility and stability profiles. New ODT technologies address many pharmaceutical and patient needs, ranging from enhanced life-cycle management to dosing for pediatric, geriatric, and psychiatric patients with dysphasia (difficulty in swallowing). This has encouraged both academia and industry to generate new orally disintegrating formulations and technological approaches in this field. The aim of this article is to review the development of ODTs, challenges in formulation, superdisintegrants employed, new ODT technologies and evaluation methodologies, suitability of drug candidates, and future prospects.

 

KEYWORDS: Orodispersible tablets (ODTs), Dysphasia, and Superdisintegrant.

 


INTRODUCTION:

The concept of orodispersible tablet emerged with an objective to improve patient’s compliance. These dosage forms rapidly disintegrate and/or dissolve to release the drug as soon as they come in contact with saliva, thus without the need for water during administration. Thereafter, the drug may get absorbed from the pharynx and esophagus or from other sections of GIT as the saliva travels down. In such cases, bioavailability is significantly greater than that observed from conventional tablet dosage form. The target populations for ODTs are pediatric, geriatric, and bedridden or developmentally disabled patients. Patients with persistent nausea, who are traveling, or who have little or no access to water are also good candidates. Difficulty in swallowing conventional tablets and capsules is common among all age groups, especially in elderly and dysphasic patients. This disorder of dysphasia is associated with many medical conditions including stroke, Parkinson’s disease, AIDS etc.

 

Orodispersible tablets are also called as orally disintegrating tablets, mouth-dissolving tablets, rapid-dissolving tablets, fast-disintegrating tablets, fast-dissolving tablets. Suitable drug candidates for such systems include neuroleptics, cardiovascular agents, analgesics, anti allergic. ODTs disintegrate and/or dissolve rapidly in saliva; therefore, water is not required during administration. Some tablets are designed to dissolve in saliva within few seconds, and are true fast-dissolving tablets. Others contain agents to enhance the rate of tablet disintegration in the oral cavity and are more appropriately termed as fast-disintegrating tablets, as they may take about one minute to disintegrate completely.

Drug Delivery to the Oral Cavity

Drug delivery via oral cavity is promising owing to ease of administration and a rich supply of blood and lymphatic vessels. In addition, this route offers high permeability to drugs and good reproducibility. Drugs absorbed via the buccal mucosa enter the systemic circulation directly through the jugular vein. This ensures a rapid onset of action and avoids first- pass liver metabolism, gastric acid hydrolysis, and intestinal enzymatic degradation1. Of the range of pharmaceutical preparations available for administration into the oral cavity, the most popular form is that of an orodispersible tablet that releases its drug contents for absorption across the oral mucosa. Various parts of oral cavity are shown in Fig.1.


 

Figure 1: Various parts of mouth (oral cavity)

 

 


Blood is richly supplied to the salivary glands and their ducts by branches of the external carotid artery and afterwards, traveling through the many branch arteries and capillaries, returns to the systemic circulation via the jugular veins. The presence of saliva in the mouth is important to drug absorption for two main reasons:

1. Drug permeation across moist (mucous) membranes occurs much more readily than across non mucous membranes.

2. Drugs are commonly administered to the mouth in the clinical setting in a solid form. The drug must, therefore, first dissolve in saliva before it can be absorbed across the oral mucosa; that is, the drug cannot be absorbed directly from a tablet.

 

Advantages of Orodispersible Tablets2

i)       Rapid disintegration of tablet results in quick dissolution and rapid absorption which provide rapid onset of action

ii)      Allows high drug loading

iii)     Alternative to liquid dosage form

iv)     Formulation is cleared from the esophagus especially in the supine position without lodging or sticking to it when swallowed, thus offering improved safety

v)      Cost effective

vi)     No risk of choking

vii)   New business opportunities; line extension, exclusively of product promotion and patent life extension

 

Characteristics of Ideal Orodispersible Tablets3

i)       They should not require water for administration yet dissolve or disintegrate in the mouth within a few seconds.

ii)      They should have pleasing mouth feel.

iii)     They should leave minimal or no residue in the mouth after oral administration.

iv)     They should allow high drug loading.

v)      They should be compatible with taste masking agents and other excipients.

vi)     They should exhibit low sensitivity to environmental conditions like humidity and temperature.

vii)   They should have sufficient mechanical strength to withstand the vigorous of the manufacturing process and post manufacturing handling.

viii)  They should be adaptable and amenable to existing processing and packaging machinery.

 

Main Ingredients Used in Preparation of ODT

Important ingredients that are used in the formulation of ODTs should allow quick release of the drug, resulting in faster dissolution. This includes both the actives and the excipients. Disintegration and solubilization of a directly compressed tablet depend on single or combined effects of disintegrants, watersoluble excipients and effervescent agents. Excipients balance the properties of the actives in FDTs. This demands a through understanding of the chemistry of these excipients to prevent interaction with the actives. Determining the cost of these ingredients is another issue that needs to be addressed by formulators. The role of excipients is important in the formulation of fastmelting tablets. These inactive foodgrade ingredients, when incorporated in the formulation, impart the desired organoleptic properties and product efficacy. Excipients are general and can be used for a broad range of actives, except some actives that require masking agents. Binders keep the composition of these fastmelting tablets together during the compression stage. The right selection of a binder or combination of binders is essential to maintain the integrity and stability of the tablet. The temperature of the excipient should be preferably around 30–35C for faster melting properties. Further, its incorporation imparts smooth texture and disintegration characteristics to the system. Binders can either be liquid, semisolid, solid or mixtures of varying molecular weights such as polyethylene glycol. The choice of a binder is critical in an orodispersible formulation for achieving the desired sensory and melting characteristics, and for the faster release of active ingredients. Commonly available fats such as cocoa butter and hydrogenated vegetable oils can also be used4.

 

The most important ingredients of orodispersible tablets are:

1. Super disintegrants:

Use of disintegrants is the basic approach in development of ODTs. Disintegrants play a major role in the disintegration and dissolution of ODT. It is essential to choose a suitable disintegrant, in an optimum concentration so as to ensure quick disintegration and high dissolution rates4. Superdisintegrants provide quick disintegration due to combined effect of swelling and water absorption by the formulation. Due to swelling of superdisintegrants, the wetted surface of the carrier increases, which promotes the wettability and dispersibility of the system, thus enhancing the disintegration and dissolution. The optimum concentration of the superdisintegrant can be selected according to critical concentration of disintegrant. Below this concentration, the tablet disintegration time is inversely proportional to the concentration of the superdisintegrant, whereas if concentration of superdisintegrant is above critical concentration, the disintegration time remains almost constant or even increases. Sodium starch glycolate, Ac-di-sol (crosscarmellose sodium), Crospovidone, Microcrystalline cellulose, Pregelatinised starch are some of examples of disintegrants.

 

Mechanism of action of Superdisintegrants

The tablet breaks to primary particles by one or more of the mechanisms listed below :

a) By capillary action

b) By swelling

c) Because of heat of wetting

d) Due to release of gases

e) By enzymatic action

f) Due to disintegrating particle/particle repulsive forces

g) Due to deformation.

 

Figure 2 :  Mechanism of Action of Superdisintegrants

 

Technologies Used To Manufacture Orodispersible Tablets

Conventional technologies

1. Freeze Drying

2. Tablet Molding

3. Spray Drying

4. Direct Compression

5. Sublimation

6. Cotton Candy Process

7. Mass Extrusion

 

Patented technologies

1. Zydis Technology

2. Durasolv Technology

3. Orasolv Technology

4. Wowtab Technology

5. Flashdose Technology

6. Flashtab Technology

Various Techniques For Orodispersible Tablets

The mouth dissolving property of the tablet is attributable to a quick ingress of water into the tablet matrix resulting in its rapid disintegration. Hence, the basic approaches to develop mouth dissolving tablets include maximizing the porous structure of the tablet matrix, incorporating the appropriate disintegrating agent, and using highly water soluble excipients in the formulation.

 

1) Freeze drying technology:

Lyophilization can be used to prepare tablets that have very porous open matrix network into which saliva rapidly moves to disintegrate lyophilized mass after it is placed in mouth. The drug is entrapped in a water soluble matrix which is freeze dried to produce a unit which rapidly disperses when placed in mouth. The preferred drug characteristics for freeze drying formulations are water insoluble, low dose, chemically stable, small particle size and tasteless. Lyophilization is relatively expensive and time consuming manufacturing process. Other drawback includes fragility, which make the use of conventional packing difficult and poor stability during storage under stressful condition3,5.

 

2) Tablet moulding technology:

Moulded tablets are designed to facilitate fast absorption of drugs through the mucosal lining of mouth by inclusion of water-soluble ingredients. The advantage of this system is that it has a porous structure which enhances dissolution (thereby enhanced bioavailability) and decreased first pass metabolism of certain drugs. As moulding process is employed usually with soluble ingredient (saccharides) which offers improved mouth feel and disintegration of tablets. However, moulded tablets have low mechanical strength, which results in erosion and breakage during handling.

 

Different moulding techniques can be used to prepare Orodispersible tablets:

a. Compression  moulding: The powder mixture previously wetted with a solvent like ethanol/water is compressed into mould plates to form a wetted mass.

b. Heat moulding: A molten matrix in which drug is dissolved or dispersed can be directly moulded into orodispersable tablets.

c. No vacuum  lyophilization: This process involves evaporation of solvent from a drug solution or suspension at a standard pressure6.

 

3) Spray drying technology:

Spray drying is used in pharmaceutical industries to produce highly porous powders. The processing solvent is evaporated rapidly by spray drying, which renders the product highly porous and thus can be used in manufacturing mouth dissolving tablets. Tablets manufactured from the spray-dried powder have been reported to disintegrate in less than 20 seconds in aqueous medium7,8.


Figure 3: Schematic view of the preparation of a porous tablet using sublimation of camphor

 

Figure 4: Schematic illustration of an orodispersible tablet prepared by the phase transition method using a higher melting sugar alcohol and a lower melting sugar alcohol.

 


4) Direct compression method:

Direct compression is a process by which tablets are compressed directly from mixtures of the drug and excipients, without any preliminary treatment9. It offers advantages over the other manufacturing processes for tablets, such as wet granulation and provides high efficiency. The mixture to be compressed must have adequate flow properties and cohere under pressure thus making pretreatment as wet granulation unnecessary. In many cases, the superdisintegrants have a major role in the disintegration and dissolution process of mouth dissolving tablets made by direct compression. The choice of a suitable type and an optimal amount of disintegrants is paramount for ensuring a high disintegration rate. The addition of other formulation components such as water soluble excipients or effervescent agents can further enhance dissolution or disintegration properties10.

 

The disintegrant addition technology (direct compression) is the most preferred technique to manufacture the tablets due to certain advantages:

a. High doses can be accommodated and final weight of the tablet can exceed that of other methods.

b. Easiest way to manufacture the tablets.

c. Conventional equipment and commonly available excipients are used

d. A limited number of processing steps are involved.

 e. Cost-effectiveness.

Tablet size and hardness strongly affect the disintegrant efficacy. Hard and large tablets have more disintegration time than normally required. Very soft and small tablets have low mechanical strength. So, an optimum kind and concentration of disintegrant should be chosen to achieve quick disintegration and high dissolution rates10,11.

 

5) Sublimation technology:

The key to rapid disintegration for mouth dissolving tablets is the presence of a porous structure in the tablet matrix. Conventional compressed tablets that contain highly water-soluble ingredients often fail to dissolve rapidly because of low porosity of the matrix. Hence, to generate porous matrix, volatile ingredients are used that are later subjected to a process of sublimation12. Sublimation is a process in which water passes directly from solid state to vapour state without passing through liquid state. This process involves addition of some inert volatile substances like urea, urethane, naphthalene, camphor, etc to other excipients and the compression of blend into tablet. Removal of volatile material by sublimation creates pores in tablet structure, due to which tablet dissolves when comes in contact with saliva. Additionally several solvents like cyclohexane, benzene etc can also be used as pore forming agents13. Various steps involved in sublimation technique for preparation of ODT are shown in Fig. 3

 

6) Mass-extrusion technology:

This technology involves softening the active blend using the solvent mixture of water soluble polyethylene glycol using methanol and expulsion of softened mass through the extruder or syringe to get a cylinder of the product into even segments using heated blade to form tablets. The dried cylinder can also be used to coat granules of bitter tasting drugs and thereby masking their bitter taste14.

 

7) Melt granulation technology:

Melt granulation technique is a process by which pharmaceutical powders are efficiently agglomerated by a meltable binder. The advantage of this technique compared to a conventional granulation is that no water or organic solvents is needed. Because there is no drying step, the process is less time consuming and uses less energy than wet granulation. It is a useful technique to enhance the dissolution rate of poorly water-soluble drugs, such as griseofulvin15. This approach to prepare MDT with sufficient mechanical integrity, involves the use of a hydrophilic waxy binder (Superpolystate, PEG-6-stearate) 16.

 

8) Phase transition process:

MDTs were produced by compressing powder containing erythritol (melting point: 122°C) and xylitol (melting point: 93-95°C), and then heating at about 93°C for 15 min(as shown in Fig.4) After heating, the median pore size of the tablets was increased and tablet hardness was also increased. The increase of tablet hardness with heating and storage did not depend on the crystal state of the lower melting point sugar alcohol17.

9) Cotton Candy Process:

The cotton candy process is also known as the “candy floss” process and forms the basis of the technologies such as Flash Dose (Fuisz Technology). An ODT is formed using a candyfloss or shear form matrix; the matrix is formed from saccharides or polysaccharides processed into amorphous floss by a simultaneous action of flash melting and centrifugal force. The matrix is then cured or partially recrystallised to provide a compound with good flow properties and compressibility. The candyfloss can then be milled and blended with active ingredients and other excipients and subsequently compressed into ODT. However the high processing temperature limits the use of this technology to thermostable compounds only18.

 

Different Patented Technologies

1) Zydis Technology: Zydis, the best known of the mouth dissolving/disintegrating tablet preparations, was the first marketed new technology tablet. Tablet is prepared by lyophilization of the drug in a matrix of water soluble carrier (eg. Gelatin). The tablet dissolves in the mouth within seconds after placement on the tongue19. More than twenty products are currently available using Zydis technology. In the U.S., they include: Claritin Reditab, Dimetapp Quick Dissolve, Feldene Melt, Maxalt-MLT, Pepcid RPD, Zofran ODT and Zyprexa Zydis.

 

Advantages

i)       The Zydis product is made to dissolve on the tongue in 2 to 3 seconds.

ii)      The Zydis formulation is self-preserving because the final water concentration in the freeze-dried product is too low to allow for microbial growth.

iii)     The combination of lyophilization and taste masking creates a product that is both pleasing to the eye and also to the senses of taste and touch.

 

Disadvantages

i) Process is expensive and time consuming.

 ii) Zydis tablets are light weight and fragile, thus unsuitable for conventional blister packaging.

iii) The Zydis formulation has poor stability at higher temperatures and humidities. If there is any pinhole or minor damage to the package, the patient may find the lyophilized product has collapsed due to absorption of moisture20.

 

2) Orasolv Technology:

OraSolv is Cima's first fastdissolving/ disintegrating dosage form. The OraSolv technology, unlike Zydis, disperses in the saliva with the aid of almost imperceptible effervescence. Orasolv technology is an oral dosage form that combines taste masked drug ingredients with an effervescent excipient system and requires conventional manufacturing process and equipment. The OraSolv technology is utilized in more than eight marketed products: four Triaminic Soft chew formulations, Tempra FirsTabs, and Remeron SolTab.

 

Advantages

i)       Orasolv dosage forms have been developed containing >1000mg of active load and are capable of combining multiple active ingredients in a tablet.

ii)      Low degree of compaction used in orasolv avoids the fracture of the particle coating being used for taste-masking. Lyophilization and high degree of compaction (used in other techniques) may disrupt such a taste-masking approach.

 

Disadvantages

i) The tablets are very soft and friable.

ii) The Orasolvtablets take 15-60 seconds to dissolve in the mouth, which is longer than fast melting oral dosage forms21.

 

3)Durasolv Technology: DuraSolv is Cima's secondgeneration mouth-dissolving/disintegrating. In this technology active ingredient is mixed into a matrix containing non-direct compression filler, a relatively high lubricant content and a wicking agent and then compressed into tablets. Durasolv is an appropriate technology for products requiring low amounts of active ingredients. DuraSolv is currently available in more than four products.

 

Advantages

i)       DuraSolv has much higher mechanical strength than Orasolv, due to the use of higher compaction pressures during tableting. The DuraSolv product is thus produced in a faster and more cost-effective manner.

ii)      DuraSolv is so durable that it can be packaged in either traditional blister packaging or vials.

 

Disadvantages

The technology is not compatible with larger doses of active ingredients, because the formulation is subjected to high compaction pressure. The structural integrity of any taste masking may be compromised with high drug doses. The drug powder coating in DuraSolv may become fractured during compaction, exposing the bitter-tasting drug to a patient's taste buds. Therefore, the DuraSolv technology is best suited for formulations including relatively small doses of active compound22.

 

4) Wowtab Technology:

The Wowtab fastdissolving/disintegrating tablet formulation has been on the Japanese market for a number of years. The Wowtab technology utilizes sugar and sugar-like (e.g., mannitol) excipients, which display high aqueous solubility and sweetness and hence, imparts taste masking and a pleasing mouth feel23. Mizumoto. et al., have classified sugar-based excipients into two types based on their mouldability and dissolution rate24.

 

Type I Saccharides: lactose and mannitol exhibit low mouldability and a high dissolution rate.

Type II Saccharides: maltose and maltitol exhibit high mouldability and low dissolution rate. The two different types of saccharides are combined to obtain a tablet formulation with adequate hardness and fast dissolution rate24,25. The Wowtab product dissolves quickly in 15 seconds or less.

 

Advantages

i) Sufficient hardness to maintain the physical characteristics of the dosage form during production until it comes in contact with moisture such as saliva in mouth.

ii) More stable to the environment than Zydis or Orasolv product due to its significant hardness.

iii) Suitable for both conventional bottle and blister packaging.

iv) The taste-masking technology utilised in Wowtab offers a superior mouthfeel due to the patented smooth melt action.

v) High dissolution rate and high mouldability due to two types of saccharides used.

 

Disadvantages

It cannot be used in patients of diabetes and other sugar related problems26.

 

5) Flashdose Technology:

Flashdose utilizes a unique spinning mechanism to produce a floss-like crystalline structure, much like cotton candy. This crystalline sugar can then incorporate the active drug and be compressed into a tablet. This procedure has been patented by Fuisz and is known as Shearform. Instead of a floss-like material, small spheres of saccharides can be produced to carry the drug. The process of making micro spheres has been patented by Fuisz, and is known as Ceform and serves as an alternative method of taste masking27.

 

6) Flash Tab Technology:

It is a rapid method to produce the disintegrable multi particulate tablet. The ingredient mixture is suitable for imparting a faster disintegration rate in the mouth (< 60 seconds), due to the presence of active substance in the form of coated micro crystals or uncoated micro granules. Coated multiparticles of active ingredients have the advantage of taste masking. These may be prepared by using conventional techniques like coacervation, micro encapsulation, and extrusion spheronisation.

 

Advantages

i)       Conventional tableting techniques are used.

ii)      The produced tablets have high mechanical strength.

iii)     Taste- masking is effectively done by coating the microcrystals28.

 

7) Quicksolv Technology:

This technology is patented by Janssen Pharmaceuticals. It utilizes two solvents in formulating a matrix, which disintegrates instantly. Methodology includes dissolving matrix components in water and the solution or dispersion is frozen. Then dry the matrix by removing water using an excess of alcohol (solvent extraction). Thus the product formed has uniform porosity and adequate strength for handling29.

 

8) Lyoc Technology:

Lyoc technology is patented by pharmalyoc. Oil in water emulsion is prepared and placed directly into blister cavities followed by freeze-drying. Non homogeneity during freeze-drying is avoided by incorporating inert filler to increase the viscosity finally the sedimentation. High proportion of filler reduces porosity of tablets due to which disintegration is lowered30.

 

9) Ziplets Technology:

Recently Eurand (Pessano con Bornago, Italy) developed the Ziplets technology, which can be used with water insoluble compounds as both bulk actives and as coated micro particles (the latter containing soluble and/or insoluble drugs). In fact, tablets composed primarily of water-soluble components often tend to dissolve rather than disintegrate, resulting in a much longer disintegration time. As the soluble components dissolve on the tablets outer layer, the rate of the water diffusion into the tablet core decreases because of the formation of concentrated viscous solutions31.

 


 

Table 1: List of various Patented technologies with their Company and Product Name

S. No.

Patented

Technology

Basis of Technology

Technology

developed by Company

Active Ingredient (Brand Names)

1

Zydis

Lyophilization

R.P.Scherer, Inc

Loratidine (Claritin Reditab and Dimetapp Quick

Dissolve).

2

Orasolv

Direct compression

Cima Labs, Inc.

Paracetamol (Tempra Quicklets),

Zolmitriptan (Zolmig Repimelt).

3

Durasolv

Direct compression

Cima Labs, Inc.

Hyoscyamine Sulfate (NuLev)

Zolmitriptan (Zolmig ZMT)

4

Wwtab

Direct compression

Yamanouchi Pharma

Tech. Inc.

Famotidine (Gaster D)

5

Flashdose

Cotton Candy Process

Fuisz Technology. Ltd.

Tramadol HCl (Relivia Flash dose)

6

Flashtab

Direct compression

Ethypharm

Ibuprofen (Nurofen FlashTab

7

Quicksolv

Lyophilization

Janssen pharmaceutics

Cisapride monohydrate (Propulsid Quicksolv),

Risperidone (Risperdal MTab)

8

Lyoc

Lyophilization

Farmalyoc

Phloroglucinol Hydrate(Spasfon Lyoc)

9

Ziplets

Direct compression

Eurand International

Ibuprofen (Cibalgina DueFast)

10

Oraquick

Micromask taste masking

KV Pharm.Co.,Inc.

Hyoscyamine Sulfate ODT

11

Advatab

Microcaps and diffuscap CR

Technology

Eurand International

AdvaTab cetrizine, AdvaTab Paracetamol

 


10) Oraquick Technology:

The Oraquick fast dissolving/disintegrating tablet formulation utilizes a patented taste masking technology. The taste masking process does not utilize solvents of any kind, and therefore leads to faster and more efficient production. Also, lower heat of production than alternative fast dissolving/disintegrating technologies makes Oraquick appropriate for heat-sensitive drugs. Oraquick claims quick dissolution in a matter of seconds, with good taste masking. There are no products using the Oraquick technology currently on the market, but KV Pharmaceutical has products in development such as analgesics, scheduled drugs, cough and cold, psycho tropics, and anti-infectives32.Various patented technologies with their company name and the list of active ingredients manufactured by them are listed here under in Table 1.

 

Evaluation Of Orodispersible Tablets 33-36

Evaluation of ODTs is done using various tests and parameters. Following tests are performed to evaluate ODTs:

1) Weight Variation: According to I.P. procedure for uniformity of weight, twenty tablets are taken and their weight is determined individually and collectively on an electronic weighing balance. The average weight of one tablet was determined from the collective weight. The weight variation test would be a satisfactory method of determining the drug content uniformity. Average weight of Tablets (mg) Maximum percentage deviation allowed 80 mg or less 10 More than 80 mg but less than 250 mg 7.5 250 mg or more 5

 

2) Thickness: Thickness of tablets is determined using Vernier caliper. An average value is calculated by using tablets in triplicate and then the mean ± standard deviation values of thickness are notified.

 

3) Tablet Hardness: Hardness of tablet is defined as the force applied across the diameter of the tablet in the order to break the tablet. The resistance of the tablet to chipping, abrasion or breakage under condition of storage transformation and handling before usage depends on its hardness. Hardness in case of MDTs is kept low to allow rapid disintegration in mouth. It is done by using hardness tester like Pfizer hardness tester or Monsanto tablet hardness tester.

 

4) Friability: Friability is measured of mechanical strength of tablets. Roche friabilator is used to determine the friability by following procedure. A pre-weighed tablet is placed in the friabilator. Friabilator consist of a plastic chamber that revolves at 25 rpm, dropping the tablets at a distance of 6 inches with each revolution. The tablets are rotated in the friabilator for 4 minutes for 100 revolutions. At the end of test, tablets are reweighed; the loss in the weight of tablet is the measure of friability and is expressed in percentage as;

 

% Friability = Loss in weight / Initial weight x 100

5) Disintegration Time: The test is carried out using the disintegration apparatus. Phosphate buffer (pH 6.8) maintained at 37ºC ± 2ºC is used as a disintegration media and the time taken for complete disintegration of the tablet with no palpable mass remaining in the apparatus is measured.

 

6) Wetting Time: A piece of tissue paper folded twice is placed in a small petridish containing 6ml. of distilled water. A tablet is carefully placed on the surface of the paper and the time required for water to reach the upper surface of the tablet is noted as the wetting time. Less is the wetting time, indicates more porous the tablet6.

 

7) Water Absorption Ratio: Water absorption ratio ‘R’ was determined using the equation, R=100 (Wb-Wa) / Wa

Where, Wa is weight of tablet before water absorption and Wb is weight of tablet after water absorption6.

 

8) In vitro Drug Release Studies: The in vitro drug release is studied using USP dissolution apparatus II (paddle type) at 50 rpm in 900 ml of phosphate buffer (pH 6.8) at 37±0.5ºC. At different time intervals, 10 ml of sample is withdrawn and filtered. An equal volume of the medium is introduced into the container after each withdrawal to maintain a constant volume. The absorbance of the samples is determined by UV Spectrophotometer at given  λ max. The mean values of drug released are plotted as cumulative % drug release vs. time.

 

CONCLUSION:

The introduction of fast dissolving dosage forms has solved some of the problems encountered in administration of drugs to the pediatric and elderly patient, which constitutes a large proportion of the world's population. ODTs are to maximize the porous structure of the tablet matrix and incorporate super disintegrating agents in optimum concentration so as to achieve rapid disintegration and instantaneous dissolution of the tablet along with good taste masking properties and excellent mechanical strength. Many drugs can be incorporated in ODT especially unpalatable drugs. The research is still going on. More products need to be commercialized to use this technology properly. Thus ODT may be developed for most of the available drugs in near future.

 

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Received on 23.12.2013       Modified on 12.01.2014

Accepted on 17.01.2014      © RJPT All right reserved

Research J. Pharm. and Tech. 7(3): Mar., 2014; Page 368-375